Method InsertEdgesIntoEdgeTable

Common/DataModel/vtkSimpleCellTessellator.cxx:1433–1635

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//------------------------------------------------------------------------------
//
void vtkSimpleCellTessellator::InsertEdgesIntoEdgeTable(vtkTriangleTile& tri)
{
  double* local = nullptr;
  vtkIdType tmp;
  vtkIdType l, r;
  vtkIdType cellId = this->GenericCell->GetId();

  constexpr double alpha = 0.5;
  assert("check: normalized alpha" && alpha > 0 && alpha < 1);

  // First setup the point reference count:
  for (int i = 0; i < 3; i++)
  {
    this->EdgeTable->IncrementPointReferenceCount(tri.GetPointId(i));
  }

  double* leftPoint = this->Scalars;
  double* midPoint = this->Scalars + this->PointOffset;
  double* rightPoint = midPoint + this->PointOffset;

  // Loop over all edges:
  // For each edge:
  //    if in hash table: incr ref
  //    else:             evaluate & put in table ref = 1
  for (int j = 0; j < 3; j++)
  {
    l = TRIANGLE_EDGES_TABLE[j][0];
    r = TRIANGLE_EDGES_TABLE[j][1];

    vtkIdType leftId = tri.GetPointId(l);
    vtkIdType rightId = tri.GetPointId(r);

    if (leftId > rightId)
    {
      // ensure that the left point has the smallest id
      // hence, evaluation occurs in the same direction in any case
      // the computations of error and interpolation will not suffer from
      // numerical precision.
      tmp = leftId;
      leftId = rightId;
      rightId = tmp;

      tmp = l;
      l = r;
      r = tmp;
    }

    double* left = tri.GetVertex(l);
    double* right = tri.GetVertex(r);

    memcpy(leftPoint + PARAMETRIC_OFFSET, left, sizeof(double) * 3);
    memcpy(rightPoint + PARAMETRIC_OFFSET, right, sizeof(double) * 3);

    // Check first in the hash table
    vtkIdType ptId = -1;

    // To calculate the edge ref count, we either:
    // - find it in the hash table